What is Thatch and How to Avoid Them

Thatch is a layer of decomposed grass and stems between the soil and the grass blades.

A layer of thatch ¼ to ½ inch thick is beneficial to the lawn. It buffers soil temperatures and adds to the resilience of the lawn, thereby reducing the compaction of soil that can result from heavy use. However, a thich layer of thatch will provide a place for insects to hide and prevent water and nutrients from reaching the grass roots where it is needed.

How do I know if thatch is a problem in my lawn?

If you walk on the lawn and it feels “spongy,” then thatch could be the cause. To be sure, take shovel and cut out a section of grass and soil. Pull it up and look at the “layer” between the grass and soil. Measure it with a ruler and if it is over ½”, then you have a thatch problem.

What to do about thatch?

See the sections on aerating and dethatching. Most likely, aerating will take care of the problem.

How to avoid thatch?

• Minimize activities that compact soil (like cars on the lawn)
• Mow frequently – don’t let the grass become excessively tall
• Follow an annual fertilizer program
• Avoid frequent, shallow waterings